Projector having light source unit including excitation light source, optical wheel, light emitting light source, and controller

ABSTRACT

A light source unit comprising an optical wheel having a plurality of segment areas and including luminescent light emitting areas where at least two luminescent material layers having different characteristics are provided in a circumferential direction, a wheel motor for driving to rotate the optical wheel, an excitation light source for shining light on to the optical wheel, a light emitting light source and a collective optical system for collecting a light beam from the optical wheel and a light beam from the light emitting light source to the same optical path, wherein the excitation light source is selectively turned on to illuminate the at least two luminescent material layers having different characteristics which are disposed on the luminescent light emitting areas, and wherein the light emitting light source is turned on for a period of time during which the excitation light source does not shine the excitation light.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority under35 USC 119 of Japanese Patent Application No, 2009-155478 filed on Jun.30, 2009 and Japanese Patent Application No. 2010-130932 filed on Jun.8, 2010, the entire disclosure of which, including the description,claims, drawings and abstract thereof, is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light source unit which includes awheel in which a luminescent material layer is provided in acircumferential direction and a projector which includes the lightsource unit.

2. Description of the Related Art

In these days, data projectors are used on many occasions as imageprojection apparatuses which project images of screens and video imagesof personal computers, as well as images of image data stored in memorycards on to a screen. These projectors are such that light emitted froma light source is caused to converge to a micromirror device called DMD(Digital Micromirror Device) or a liquid crystal plate for display of acolor image on the screen.

In projectors of the type described above, conventionally, projectorsusing a high-intensity discharge lamp as a light source have been themainstream of projectors. In recent years, however, there have been mademany developments and proposals on light source units which utilize asemiconductor light emitting device such as a light emitting diode(LED), a laser diode (LD), or a device utilizing organic EL technologyas a light emitting device of a light source unit.

Japanese Unexamined Patent Publication No. 2004-220015(JP-A-2004-220015) proposes a light source unit which includes lightemitting devices and in which the light emitting devices are disposed ina matrix configuration in order to increase the quantity of light. Inthe invention of the patent document, however, bright points of thelight emitting devices are increased, and therefore, the convergence oflight emitted from the respective bright points to a single point by anoptical system arranged downstream of the light emitting devices becomesdifficult, leading to a problem that the light utilization efficiency oflight emitted from the respective light emitting diodes is reduced.

In addition, Japanese Unexamined Patent Publication No. 2004-341105(JP-A-2004-341105) proposes a light source unit which includes anoptical wheel in which luminescent materials are disposed in acircumferential direction and an ultraviolet light emitting diode. Thelight source unit proposed in this patent document is configured so thatultraviolet light is shone on to the optical wheel from El rear surfaceside thereof as excitation light and light emitted from a front surfaceside of the optical wheel is utilized as light source light.

A light source unit that is to be used in a projector is required togenerate at least light of wavelength bands of red, green and blue,which are the three primary colors of light. In a configuration whichutilizes an optical wheel like one shown in JP-A-2004-341105, the threeprimary colors of light can be generated by disposing a red luminescentmaterial layer, a green luminescent material layer and a blueluminescent material layer are disposed end to end in a circumferentialdirection of the optical wheel.

However, in the light source unit which utilizes the optical wheel inthe red luminescent material layer, the green luminescent material layerand the blue luminescent material layer are disposed end to end in thecircumferential direction, there is a problem inherent therein that inthe event of the luminescent material layers of the respective colorsare disposed uniformly, there has existed a problem that a difference inluminance between light beams of red, green and blue wavelength bands isincreased.

Then, there is proposed a light source unit in which at least aplurality of luminescent material layers are disposed end to end in acircumferential direction of an optical wheel, a blue laser emitter isused as an excitation light source, and an independent light emittingdevice is added further as alight emitting light source.

In the light source unit configured in the way described above, thedifference in luminance between the light beams having differentwavelength bands can be reduced. However, since the non-use area iscaused on the optical wheel, an effective use of this area has been aproblem to be solved.

SUMMARY OF THE INVENTION

An object of the invention is to provide a light source unit whichutilizes an optical wheel in which an excitation light source and atleast a plurality of luminescent material layers are disposed end to endin a circumferential direction and an independent light emitting lightsource, wherein an effective use of the optical wheel is realized byforming an additional different luminescent material layer in a non-usearea on the optical wheel and a projector which includes the lightsource unit.

With a view to attaining the object, according to an aspect of theinvention, there is provided a light source unit comprising:

an optical wheel having a plurality of segment areas and includingluminescent light emitting areas where two or more luminescent materiallayers having different characteristics are provided end to end incircumferential direction;

a wheel motor for driving to rotate the optical wheel;

an excitation light source for shining light on to the optical wheel asexcitation light or as light of a predetermined wavelength band;

a light emitting light source provided out of an optical path of theoptical wheel; and

a collective optical system for collecting a light beam emitted from theoptical wheel and a light beam emitted from the light emitting lightsource for convergence to the same optical path, wherein

the excitation light source is selectively turned on to selectivelyilluminate the two or more luminescent material layers having differentcharacteristics which are disposed on the luminescent light emittingareas by discriminating the luminescent material layers into an area onto which the excitation light is shone and an area on to which theexcitation light is not shone, and wherein the light emitting lightsource is turned on for a period of time during which the excitationlight source does not shine the excitation light.

With a view to attaining the object, according to another aspect of theinvention, there is provided a projector comprising a light source unit,a light guiding unit, a display device, a projection optical system, anda projector control is having a light source control means and a displaydevice control means, wherein projection in different projection modeincluding a primary projection mode and a secondary projection mode isenabled, and wherein the light source unit is a light source unit as setforth in any of claims 1 to 7 and is disposed so that light source lightis caused to converge to an incident plane of the light guiding unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an external appearance of aprojector according to an embodiment of the invention,

FIG. 2 is a functional circuit block diagram of the projector accordingto the embodiment of the invention,

FIG. 3 is an exemplary plan view showing an internal construction of theprojector according to the embodiment of the invention,

FIG. 4 is an exemplary plan view of a light source unit according to theembodiment of the invention,

FIG. 5 is an exemplary front view of an optical wheel according to theembodiment of the invention,

FIG. 6 shows explanatory diagrams which explain a control method of thelight source unit in the projector according to the embodiment of theinvention, and

FIG. 7 shows emission spectrum examples of green luminescent materialswhich can emit light of green wavelength bands according to theembodiment of the invention,

FIG. 8 is an exemplary plan view of a main part of a light source unitaccording to another embodiment of the invention,

FIG. 9 is an exemplary front view of an optical wheel according toanother embodiment of the invention,

FIG. 10 shows explanatory diagrams which explain a control method of thelight source unit in the projector according to another embodiment ofthe invention,

FIG. 11 is an exemplary front view of another optical wheel according toanother embodiment of the invention, and

FIG. 12 shows explanatory diagrams which explain another control methodof the light source unit in the projector according to anotherembodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, an embodiment of the invention will be described in detailby reference to the accompanying drawings. FIG. 1 is a perspective viewshowing an external appearance of a projector 10. In this embodiment,left and right denote, respectively, left and right directions withrespect to a projecting direction, and front and rear denote,respectively, front and rear directions with respect to a travelingdirection of a light beam. The projector 10 of the embodiment enablesprojection in different modes including a primary projection mode and asecondary projection mode.

As is shown in FIG. 1, the projector 10 has a substantially rectangularparallelepiped shape and has a lens cover 19 which covers a projectionport which lies to a side of a front panel 12 which is referred to as afront side panel of a main body case, as well as a plurality of insideair outlet holes 17 in the front panel 12. Further, although not shown,the projector 10 includes an Ir reception part for receiving a controlsignal from a remote controller.

In addition, a keys/indicators part 37 is provided on an upper sidepanel 11 which makes up the main body case. Disposed on thiskeys/indicators part 37 are keys and indicators which include a powersupply switch key, a power indicator which informs whether the powersupply is on or off, a projection switch key which switches on or offprojection, an overheat indicator which informs of an overheat conditionwhen the light source unit, the display device or the control circuitoverheats and the like.

Further, provided on a back side or a back side panel of the main bodycase are an input/output connectors part where USB terminals, an imagesignal input terminal, an S terminal, an RCA terminal and the like areprovided and various types, of terminals 20 including a power supplyadaptor plug and the like. A plurality of outside air inlet holes 18 areformed in proximity to respective lower portions of a right-hand sidepanel 14 which constitutes a side panel, not shown, of the main bodycase and a left-hand side panel 15 which is a side panel shown in FIG.1.

Next, a projector control means for the projector 10 will be describedby use of a block diagram in FIG. 2. The projector control means is madeup of a control unit 38, an input/output interface 22, an imagetransform part 23, a display encoder 24, a display drive part 26 and thelike. In addition, image signals of various standards that are enteredfrom the input/output connector part 21 are sent via the input/outputinterface 22 and a system bus (SB) to the image transform part 23 wherethe image signals are transformed so as to be unified into an imagesignal of a predetermined format which is suitable for display.Thereafter, the image signals so transformed are then outputted to thedisplay encoder 24.

The control unit 38 governs the control of respective operations ofcircuitries within the projector 10 and is made up of a CPU, a ROM whichstores in a fixed fashion operation programs of various types ofsettings and a RAM which is used as a work memory.

In addition, the display encoder 24 deploys the image signals enteredthereinto on a video RAM 25 for storage therein and generates a videosignal from tree contents stored in the video RAM 25, outputting thevideo signal so generated to the display drive part 26.

The display drive part 26 functions as a display device control meansfor driving a display device 51 which is a spatial optical modulator(SOP) at an appropriate frame rate in accordance with the image signaloutputted from the display encoder 24. A light beam emitted from a lightsource unit 63 is shone on to the display device 51 via a light sourceoptical system to thereby form an optical image by reflected lightreflected at the display device 51, and the image so formed is thenprojected on to a screen, not shown, for display via a projectionoptical system 90, which will be described later. A movable lens group97 of the projection optical system 90 is driven by a lens motor 45 forzooming or focusing.

In addition, an image compression/expansion part 31 performs a recordingoperation in which a luminance signal and a color-difference signal aredata compressed through processings such as ADCT and Huffman coding soas to write them sequentially on a memory card 32 which is referred toas a detachable recording medium. Further, the imagecompression/expansion part 31 performs an operation in which when in areproducing mode, the image compression/expansion part 31 reads outimage data recorded on the memory card 32 and expands individual imagedata which make up a series of dynamic images frame by frame. Then, theimage data is outputted to the display encoder 24 via the imagetransform part 23 so as to enable the display of dynamic images on thebasis of the image data stored on the memory card 32.

Operation signals generated at the keys/indicators part 37 which is madeup of the main keys and indicators provided on the upper side panel 11of the main body case are sent out directly to the control unit 38,while key operation signals generated by operating keys on the remotecontroller are received by the Ir reception part 35, and a code signaldemodulated at an Ir processing part 36 is outputted to the control unit38.

In addition, an audio processing part 47 is connected to the controlunit 38 via the system bus (SB). This audio processing part 47 includesa sound source circuit such as a PCM sound source. When in a projectionmode and a reproducing mode, the audio processing part 47 converts audiodata into analog signals and drives a speaker 48 to output loudly soundor audio based on the audio data.

Additionally, the control unit 38 controls a light source controlcircuit 41 which constitutes a light source control means. This lightsource control circuit 41 controls the light source unit 63 so thatlight of a predetermined wavelength band that is required at the time offorming an image is emitted from the light source unit 63. Specifically,when light of a red wavelength band is required, the light sourcecontrol circuit 41 turns off an excitation light source 72, which willbe described later, and turns on a light emitting light source as a redlight source. In addition, when light of a green wavelength band isrequired, the light source control circuit 41 turns on the excitationlight source 72 and controls the wheel motor 73 so that a firstluminescent light emitting area 2 or a second luminescent light emittingarea 3 is positioned on an optical axis of excitation light. Further,when light of a blue wavelength band is required, the light sourcecontrol circuit 41 turns on the excitation light source 72 and controlsthe wheel motor 73 so that a diffusion and transmission area 1 ispositioned on the optical axis of the excitation light.

Further, the control unit 38 causes a cooling fan drive control circuit43 to detect temperatures through a plurality of sensors which areprovided at the light source unit 63 and the like so as to control therotational speed of the cooling fan based on the results of thetemperature detection. In addition, the control unit 38 also causes thecooling fan drive control circuit 43 to make the cooling fan continue torotate even after the power supply of the projector main body isswitched off by use of a timer or the like or to make the power supplyto the projector main body be cut off depending upon the results of thetemperature detection by the temperature sensors.

Next, an internal construction of the projector 10 will be described.FIG. 3 is an exemplary plan view showing an internal construction of theprojector 10. As is shown in FIG. 3, in the projector 10, a light sourcecontrol circuit board 102 is disposed in proximity to the right-handside panel 14 and a power supply circuit block 101 and the like aremounted on this light source control circuit board 102. A siroccofan-type blower 110 is disposed substantially at a center in theprojector 10, and a control circuit board 103 is disposed in proximityto the blower 110. The light source 63 is disposed in proximity to thefront panel 12, and an optical system unit 70 is disposed in proximityto the left-hand side panel 15.

Additionally, an interior of a housing of the projector 10 is dividedairtightly into an inlet side space compartment 121 which lies on theback panel 13 side and an outlet side space compartment 122 which lieson the front panel 12 side by a portioning bulkhead 120. The blower 110is disposed so that its outside air inlet port 111 is positioned in theinlet side space compartment 121 and its outside air outlet port 113 ispositioned on a boundary between the outlet side space compartment 122and the inlet side space compartment 121.

The optical system unit 70 has a substantially U-shape and is made up ofthree blocks such as an illumination block 78 which is positioned inproximity to the light source unit 63, an image generation block 79which is positioned on the back panel 13 side, and a projection block 80which is positioned between the illumination block 78 and the:left-hardside panel 15.

The illumination block 78 includes part of a light solar source opticalsystem 62 for guiding light emitted from the light source unit 63 to thedisplay device 51 which is included in the image generation block 79.The part of the light source optical system 62 that is included in theillumination block 78 includes a light guiding unit 75 for making alight beam emitted from the light source 63 into a light beam whoseintensity is uniformly distributed and a collective lens for collectinglight that has passed through the light guiding unit 75 forconcentration.

The image generating block 79 has, as the light source optical system62, an optical axis varying mirror 76 for varying a direction of anoptical axis of a light beam that has emerged from the light guidingunit 75, a plurality of collective lenses for collecting light beamsreflected by the optical axis varying mirror 76 for concentration on thedisplay device 51 and a shining mirror 84 for shining the light beamsthat have passed through the collective lenses on to the display device51 at a predetermined angle. Further, the image generating block 79includes a MD which is configured as the display device 31, and adisplay device cooling device 53 for cooling the display device 51 isdisposed on a back panel 13 side of the display device 51 to therebyprevent the display device 51 from being heated to a high temperature.

The projection block 80 has a lens group of a projection optical system90 which project, light on to the screen, which light is reflected bythe display device 51 to form an image. The projection optical system 90constitutes a variable focus lens made up of a fixed lens group 93 whichis incorporated in a fixed lens barrel and a movable lens group 97 whichis incorporated in a movable lens barrel and having a zooming function.This variable focus lens enables zooming and focusing operations bymoving the movable lens group 97 by a lens motor.

Next, the light source unit 63 of the projector 10 according to theembodiment will be described. FIG. 4 is an exemplary plan view of thelight source unit 63. As is shown in FIG. 4, the light source unit 63includes a plurality of excitation light sources 72 which are disposedso that their optical axes become parallel to an axis of the lightguiding unit 75, a plurality of collimator lenses 149 which are disposedin front of the excitation light sources 72, and a group of reflectingmirrors 150 for changing directions of optical axes of light beams thatpass through the collimator lenses 149 at 90 degrees.

to addition, the light source unit 63 has an optical wheel 71 which isdisposed on an optical axis of excitation light reflected on thereflecting mirror system 150 so that a rot ting of the optical cancel 71becomes parallel to the optical axis of excitation light, a wheel motor73 which drives to rotate the optical wheel 71, a red light source (74)which is a light emitting light source 74 which is disposed so that anoptical axis direction of excitation light when it is emitted from theexcitation light source 72 becomes parallel to an optical axis of lightemitted from the light emitting light source 74, and a collectiveoptical system for collecting light beams emitted from the optical wheel71 and the red light source (74) for concentration on a predeterminedplane by matching the optical axis of the light beam emitted from theoptical wheel 71 with the optical axis of the light beam emitted fromthe red light source (74).

In the excitation light sources 72, a plurality of blue laser emittersare arranged in a planar configuration to emit laser light of a bluewavelength band to the optical wheel 71 as excitation light and light ofa blue wavelength band. In addition, the collimator lenses 149 emitforwards light emitted individually from the plurality of blue laseremitters of the excitation light sources 72 as parallel light at thefront of the blue laser emitters. Further, the reflecting mirror system150 is made up of a plurality of strip-like reflecting mirrors which arearranged into a step-like configuration to reflect light emitted fromthe excitation light sources 72 so that optical axes of light beamsemitted from the excitation light sources 72 are change through 90degrees.

As is shown in FIG. 5, the optical wheel 71 includes a diffusion andtransmission area 1 for diffusing light emitted from the excitationlight sources 72, a primary luminescent light emitting area 2 and asecondary luminescent light emitting area 3, and these areas arearranged end to end in a circumferential direction. In addition, in theoptical wheel 71, a bandlike diffusion and transmission layer 1 a isformed in a position lying in proximity to an outer circumferential edgeof the diffusion and transmission area 1. In addition, a band-likeprimary luminescent material layer 2 a is formed in a position lying inproximity to an outer circumferential edge of the primary luminescentlight emitting area 2. Further, a band-like secondary luminescentmaterial layer 3 a is formed in a position lying in proximity to anouter circumferential edge of the secondary luminescent light emittingarea 3. These layers 1 a, 2 a, 3 a are arranged end to end in thecircumferential direction to thereby form a ring.

The diffusion and transmission layer 1 a of the optical wheel 71 isformed of a material such as glass having a high light transmissionproperty. A sand blasting treatment is applied to a surface of thediffusion and transmission layer 1 a to thereby transmit light from theexcitation light sources 72 while diffusing it. In addition, the primaryluminescent material layer 2 a is a green luminescent material layerwhich is formed by scattering green luminescent materials uniformly in abinder sot is adapted to emit luminescent light of a green wavelengthband by utilizing light emitted from the excitation light sources 72 asexcitation light.

Further, the secondary luminescent material layer 3 a is a greenluminescent material layer which is formed by scattering greenluminescent materials having a different hue from that of the primaryluminescent material layer 2 a uniformly in a binder.

Then, the primary luminescent material layer 2 a and the secondaryluminescent material layer 3 a emit luminescent light in every directionby receiving excitation light emitted from the excitation light sources72. In addition, a mirror treatment is given to a front surface of theoptical wheel 71 at the areas where the primary luminescent materiallayer 2 a and the secondary luminescent material layer 3 a are disposedso that the front surface at those areas is formed as a reflectingsurface. By forming the reflecting surface on the front surface of theoptical wheel 71, luminescent light emitted to the front surface side ofthe optical wheel 71 is also reflected on the front surface of theoptical wheel 71 so as to be emitted back towards the excitation lightsources 72, and therefore, the utilization efficiency of luminescentlight can be increased.

Namely, the optical wheel 71 of the embodiment has the plurality ofsegment areas, which include the luminescent light emitting areas wheretwo or more luminescent material layers having different properties arearranged end to end in the circumferential direction.

The light emitting light source 74 is a red light source (74) such as ared light emitting diode which emits light of a red wavelength band.Then, this red light source (74) is disposed in a position lying betweenthe excitation light sources 72 and the optical wheel 7i so that anoptical axis direction of excitation light when it is emitted from theexcitation light sources 72 and an optical axis direction of lightemitted from the red light source (74) becomes parallel to each other.

In addition, the collective optical system includes a mirror system 151which is made up of a plurality of mirrors, a convex lens system 153which is made up of a plurality of convex lenses, a collective lenssystem 155 which is made up of collective lenses each of which is madeby a combination of convex lenses, and a light guiding unit incidentlens 154. The mirror system 151 includes a primary mirror 151 a which isdisposed in a position where an optical axis of excitation light whichis reflected on the reflecting mirror system 150 and an optical axis ofthe red light source (74) intersect each other at right angles, asecondary mirror 151 b which is disposed in a position which is situatedon a is surface side of the optical wheel 71 and where an extension ofan axis of the light guiding unit 75 and an extension of the opticalaxis of the excitation light which is reflected on the reflecting mirrorsystem 150 intersect each other at right angles, a tertiary mirror 151 cwhich is disposed or the optical axis of the red light souse (74) and aquaternary mirror 151 d which is disposed in a position where an opticalaxis of light of a red wavelength band which is reflected on thetertiary mirror 131 c and the extension of the axis of the light guidingunit 75 intersect each other at right angles.

The primary mirror 151 a is a dichroic mirror which allows for passageof light emitted from the excitation light sources 72 and the red lightsource (74) and reflects luminescent light emitted from the opticalwheel 71. In addition, the secondary mirror 151 b is a reflecting mirrorwhich makes the optical axis of light which is emitted from theexcitation light sources 74 and which then passes through the opticalwheel 71 while being diffused coincide with the axis of the lightguiding unit 75. The tertiary mirror 151 c is a reflecting mirror whichreflects light emitted from the red light source (74) and luminescentlight emitted from the optical wheel 71 towards the quaternary mirror151 d. The quaternary mirror 151 d is a dichroic mirror which allows forpassage of a light beam reflected by the secondary mirror 151 b andreflects light beam reflected by the tertiary mirror 151 c.

In addition, the convex lens system 153, which constitutes thecollective optical system, includes a primary convex lens 153 a which isdisposed between tree excitation light sources 72 and the primary mirror151 a, a secondary convex lens 153 b which is disposed between thesecondary mirror 151 b and the quaternary mirror 151 d, a tertiaryconvex lens 153 c which is disposed between the primary mirror 151 a andthe tertiary mirror 151 c, and a quaternary convex lens 1534 which isdisposed between the tertiary mirror 151 c and the quaternary mirror 151d.

Further, the collective lens system 155, which constitutes thecollective optical system, includes the collective lens which isdisposed in proximity to the red light source (74) and the collectivelens which is disposed in proximity to front and rear surface sides ofthe optical wheel 71 and on the optical axis of light emitted from theexcitation light sources 72 for convergence of light emitted from thered light source and the optical wheel 71. In addition, the lightguiding unit incident lens 154, which constitutes the collective opticalsystem, is disposed in proximity to the light guiding unit 75 forconvergence of light emitted from the light source unit 63 to anincident plane of the light guiding unit 75.

Then, in the light source unit 63 configured as described above, bluelaser light emitted from the excitation light sources 72 and reflectedon the reflecting mirror system 150 is caused to converge by the primaryconvex lens 153 a. Thereafter, the convergent light passes through theprimary mirror 151 a and is shone on to the luminescent light reflectingareas and the diffusion and transmission area on the optical wheel 71 bythe collective lens system 155. In addition, light beams emitted fromthe excitation light sources 72 and shone on to the primary luminescentlight emitting area 2 or the secondary luminescent light emitting area 3excite the luminescent material as excitation light, and the luminescentmaterial so excited then emits light of a predetermined wavelength band.Further, light beams emitted from the excitation light sources 72 andshone on to the diffusion and transmission area on the optical wheel 71are diffused and are then converted in nature from coherent light intoincoherent light so as to be emitted from the rear surface side of theoptical wheel 71 as light of a blue wavelength band which is incoherentlight.

Additionally, light of a red wavelength band which is emitted from thered light source (74) is caused to converge by the collective lenssystem 155 and passes through the primary mirror 151 a. Luminescentlight of the green wavelength band emitted from the optical wheel 71towards the excitation light sources 72 is caused to converge by thecollective lens system 155 so as to be shone on to the primary mirror151 a. Then, the light of the red wavelength band that has passedthrough the primary mirror 151 a and the luminescent light that has beenreflected on the primary mirror 151 a are caused to converge by thetertiary convex lens 153 c and the quaternary convex lens 153 d and arereflected on the tertiary mirror 151 c and the quaternary mirror 151 dso as to be cause to converge to the incident plane of the light guidingunit 75 by the light guiding unit incident lens 154 to enter the lightguiding unit 75.

Further, the light of the blue wavelength band that has passed throughthe optical wheel 71 while being diffused is caused to converge so as tobe shone on to the secondary mirror 151 b by the collective lens system155. The light of the blue wavelength band is then reflected on thesecondary mirror 151 b, is caused to converge by the secondary convexlens 153 b and passes through the quaternary mirror 151 d. Thereafter,the light of the blue wavelength band is caused to converge to theincident plane of the light guiding unit 75 by the light guiding unitincident lens 154 so as to enter the light guiding unit 75.

Namely, luminescent light of the green wavelength band and light of theblue wavelength band emitted from the optical wheel 71 and light of thered wavelength band emitted from the red light source 74 passes throughand/or are reflected on the quaternary mirror. Thereafter, light of theaforementioned wavelength bands are collected to the same optical pathand then are caused to converge to the quaternary convex lens 153 d soas to enter into the light guiding unit 75.

Next, the control of the light source unit 63 in the projector 10 willbe described. FIG. 6 shows explanatory diagrams which explain a controlmethod of the light source unit 63 in the projector 10. As has beendescribed before, according to the projector 10 of the embodiment, theprojection is enabled in the two projection modes of different hueswhich are made up of the primary projection mode and the secondaryprojection mode. Namely, the projector 10 can implement projections byswitching between the primary projection mode which utilizes the primaryluminescent light emitting area 2 on the optical wheel 71 and thesecondary projection mode which utilizes the secondary luminescent lightemitting area 3 whose hue is different from that of the primaryprojection mode by controlling the light source control circuit 41 thathas been described above by the projector control means.

Hereinafter, a specific control of the light source control circuit 41by the projector control means will be described. As is shown in FIG.6A, in the event of the primary projection mode, the projector controlmeans makes the light source control circuit 41, functioning as thelight source control means, execute a control of turning on theexcitation light sources 72 and turning off the red light source (74)when the diffusion and transmission area 1 of the optical wheel 71 ispositioned on the optical axis of excitation light and when the primaryluminescent light emitting area 2 of the optical wheel 71 is positionedon the optical axis of excitation light. In addition, the projectorcontrol means makes the light source control circuit 41 execute acontrol of turning off the excitation light sources 72 and turning onthe red light source (74) when the secondary luminescent light emittingare 3 of the optical wheel 71 is positioned on the optical axis ofexcitation light.

To be specific, in the event of light being emitted from the lightsource unit 63 in the primary projection mode, light of the bluewavelength band, light of the green wavelength band and light of the redwavelength band are emitted sequentially from the light source unit 63in that order. Consequently, in the event of the primary projectionmode, the projector control means makes the display drive part 26,functioning as the display device control means, control the displaydevice 51 so as to generate images in the order of light of the bluewavelength band, light of the green wavelength band and light of the redwavelength band.

Additionally, as is shown in FIG. 6B, in the event of the secondaryprojection mode, the projector control means makes the light sourcecontrol means execute a control of turning on the excitation lightsources 72 and turning off the red light source (74) when the diffusionand transmission area 1 of the optical wheel 71 is positioned on theoptical axis of excitation light and when the secondary luminescentlight emitting area 3 of the optical wheel 71 is positioned on theoptical axis of excitation light addition, the projector control meansmakes the light source control circuit 41 execute a control of turningoff the excitation light sources 72 and turning on the red light source(74) when the primary luminescent light emitting area 2 of the opticalwheel 71 is positioned on the optical axis of excitation light.

To be specific, in the event of light being emitted from the lightsource unit 63 in the secondary projection mode, light of the bluewavelength band, light of the red wavelength band and light of the greenwavelength band are emitted sequentially from the light source unit 63in that order. Consequently, in the event of the secondary projectionmode, the projector control means makes the display device control meanscontrol the display device 51 so as to generate images in the order oflight of the blue wavelength band, light of the red wavelength band andlight of the green wavelength band.

Thus, according to the projector 10 of the embodiment, image projectionsin the different projection modes are enabled by making effective use ofthe area of the optical wheel 71 that s not conventionally used andcontrolling the light source control circuit 41 and the display drivepart 26 by the projector control means.

In addition, in the light source unit 63 which includes the opticalwheel 71, the excitation light sources 72 and the light emitting lightsource 74, the optical wheel 71 is made up of the primary luminescentlight emitting area 2, the secondary luminescent light emitting area 3and the diffusion and transmission area 1. In addition, the luminescentmaterial layer which emits light of the predetermined wavelength band isformed on the secondary luminescent light emitting area 3. Thus, thedifferent luminescent light can be obtained by use of the area that isnot conventionally used.

Further, according to the light source unit 63 of the embodiment, theblue laser light emitters are used as the excitation light sources. Thisenables light having high energy to be used as excitation light, therebymaking it possible to increase the excitation efficiency of theluminescent materials. In addition, the red light emitting diode is usedas the light emitting light source 74 and the green luminescent materialis used on the primary luminescent material layer 2 a. This enableslight of the predetermined wavelength band to be obtained with goodefficiency.

In addition, according to the light source unit 63 of the embodiment,the primary luminescent material layer 2 a is made of a luminescentmaterial having an emission spectrum characteristic shown in FIG. 7Awhich has a peak wavelength of 570 nm and a wavelength band athalf-power point of 130 nm. In addition, the secondary luminescentmaterial layer 3 a is made of a luminescent material having an emissionspectrum characteristic shown in FIG. 71 which has a peak wavelength of515 nm and a wave length at half-power point of 30 nm. Thus, the lightsource unit 63 can be provided which can emit two types of light ofdifferent greed wavelength bands and having different hues.

Further, the front surfaces of the portions of the optical wheel 71where the primary luminescent light emitting area 2 and the secondaryluminescent light emitting area 3 are formed or at least the frontsurfaces of the areas of the portions of the optical wheel 71 where thesecondary luminescent material layer 2 a and the secondary luminescentmaterial layer 3 a are disposed are formed as the reflecting planes. Byadopting this configuration, light beams emitted from the luminescentmaterials towards the front surface side of the optical wheel 71 canalso be made to be effective light by being reflected on the reflectingplanes. Therefore, the utilization efficiency of light emitted can beincreased.

Thus, according to the projector 10 which uses the light source unit 63which is configured as described above, different types of white lightcan be produced by switching the projection modes. For example, when theprojector 10 is used in a bright environment, a projection with a highluminance mode in which lightness is high can be enabled, whereas in adark environment, a projection with a mode in which the color purity ofgreen is high can be enabled.

Further, since the different projection modes are made to be realized bychanging light emitted from the light source unit 63, compared with a(configuration in which projection modes are changed by correctingimages by CPU or the like, the load borne by the CPU can be reduced.

Note that the invention is not limited to the embodiment where thesecond luminescent material layer 3 a is the green luminescent materiallayer which can emit light of the green wavelength band whose hue isdifferent from that green light emitted from the primary luminescentmaterial layer 2 a. For example, the optical wheel 71 can be configuredas having a secondary luminescent material layer 3 a which is a greenluminescent material layer which can emit light of a green wavelengthband by forming the green luminescent material layer of the sameluminescent material as that of the primary luminescent material layer 2a with a different ratio at which the green luminescent material iscontained in the luminescent material layer.

Further, in the embodiment, while the different luminescent materialsare used to emit the two types of light of the green wavelength bandswhich have the different hues, the invention is not limited thereto. Forexample, two types of light of green wavelength bands may be used whichhave different quantum efficiencies.

Further, two types of light of groan wavelength bands may be used whichhave different quantum efficiencies with respect to temperature. As thisoccurs, although not illustrated, a temperature sensor is provided, andthe projection modes are switched based on the temperature detected.

Furthermore, a secondary luminescent material layer 3 a may be a greenluminescent material layer which can emit light of a green wavelengthband by forming the secondary material layer 3 a of the same luminescentmaterial of the primary luminescent material layer 2 a with the sameratio as that of the primary luminescent material layer 2 a at which theluminescent material is contained in the luminescent material layer butwith a different thickness at which the secondary luminescent materiallayer 3 a is disposed.

In addition, in the light source unit 63 of the embodiment, the primaryluminescent material layer 2 a. and the secondary luminescent materiallayer 3 a are the green luminescent material layers which can emit thetwo types of light of the green wavelength bands which have thedifferent hues. However, the invention is not limited thereto. Forexample, the optical wheel 71 can be configured as having a primaryluminescent material layer 2 a and a secondary luminescent materiallayer 3 a which constitute the same luminescent material layers 2 a, 3a. To be specific, the same green luminescent material layers are formedon the primary luminescent light emitting area 2 and the secondaryluminescent light emitting area 3 of the optical wheel 71.

According to the light source unit which includes the optical wheel 71described above, the deterioration with age of the green luminescentmaterial on to which the blue laser light having high directivity isshone and the binder can be suppressed, whereby the light source unit 63can be provided which can maintain its performance over a long period oftime.

Further, in the embodiment, the red light emitting diode is used as thelight emitting light source 74, and the green luminescent materials areused in the primary luminescent material layer 2 a and the secondaryluminescent material layer 3 a. However, the invention is not limitedthereto. For example, a configuration can also be adopted in which agreen light emitting diode is used as the light emitting light source 74and a red luminescent material is used on the optical wheel 71.

Note that in the event that image projections in the differentprojection modes are performed in the projector 10, a configuration maybe adopted in which the optical wheel 71 is rotated reversely bycontrolling the light source control means by the projector controlmeans. To be specific, in the event of the primary projection mode,similar control to the control shown in FIG. 6A, is performed. However,in the event of the secondary projection mode, the projector controlmeans makes the light source control means execute a control of rotatingthe wheel motor 73 reversely.

In this way, by adopting the configuration in which in the secondaryprojection mode, the wheel motor 73 is rotated reversely to the rotatingdirection thereof in the primary projection mode, when light is emittedfrom the light source unit 63, light of the blue wavelength band, lightof the green wavelength band and light of the red wavelength band areemitted sequentially from the light source unit 63 in that order at alltimes. Consequently, since the display drive part 26 may only have tocontrol the display device 51 in the same way whether the primaryprojection mode or the secondary projection mode is used, the way ofcontrolling the display device 51 does not have to be changed dependingupon the projection mode used, thereby making it possible to projectimages in the different projection modes only by controlling the lightsource unit 63.

As this occurs, the optical wheel 71 is in such a state that the primaryluminescent light emitting area 2 and the secondary luminescent lightemitting area 3 are disposed in an axial symmetrical fashion withrespect to a center line of the diffusion and transmission area 1.

Then, according to the projector 10 which is controlled in the waydescribed above by the projector control means, the way of controllingthe display device 51 is not changed whether the primary projection modeor the secondary projection mode is used due to the switching betweenthe primary projection mode and the secondary projection mode beingimplemented by reversing the rotating directions of the optical wheel71. Thus, the load borne by the CPU or the like can be reduced.

In addition, as an independent light emitting light source, a lightsource unit 63′ may be configured by utilizing two light emitting lightsources 74 consisting of a red light source (74 a) and a blue lightsource (74 b), and not providing the diffusion and transmission portionbut providing more than three types of the green light emittingluminescent materials on the optical wheel 71.

This light source unit 63′ emits light of a red wavelength band which isemitted from the red light source (74 a) as the light emitting lightsource 74 so that the light beam becomes parallel to the front panel 12.The light source unit 63′ includes the wheel motor 73 and an opticalwheel 71′ which are disposed in proximity to the inside of the frontpanel 12.

Additionally, as shown in FIG. 8, excitation light from the excitationlight source 72 is shone on to the optical wheel 71′ via a convex lensand a concave lens as a convergence lens 156 for causing a light beam ofemitted light to converge which is a parallel light beam from theexcitation light source 72, not shown.

The collective lens system 155 is disposed lust proximal to anexcitation light source side of the optical wheel 71′. Light emittedfrom the excitation light source 72 is caused to converge so as to beincident into a luminescent material on the optical wheel 71′, andluminescent light emitted from the optical wheel 71° is caused toconverge go as to emitted to the excitation light source side by thecollective les system. 155.

The light source unit 63′ emits light of a red wavelength band from thered light source (74 a) via the collective lens system 155 which isdisposed just in front of the red light source (74 a). A primarydichroic mirror 151 e is disposed in a position where an optical axis oflight of the red wavelength band emitted from the red light source (74a) and an optical axis of light of a green wavelength band emitted fromthe optical wheel 71 intersect each other.

The primary dichroic mirror 151 e allows light of the red wavelengthband and light of the blue wave length band which is excitation light topass through and reflects light of the green wavelength band. Due to theproperty, light of the green wavelength band is reflected on the primarydichroic mirror 151 e. Light of the green wavelength band so reflectedtravels towards a left-hand side panel 15 of the projector 10 withmaking its optical axis coincide with the optical is of light of the redwavelength band.

In addition, the light source unit 63′ includes a blue light source (74b) as the light emitting light source 74 which is a light emitting diodein proximity to the reside of the front panel 12 on the optical axis ofthe light guiding unit 75.

The collective lens system 155 is disposed in proximity to the bluelight source (74 b). Light of the blue wavelength band emitted from theblue light source (74 b) is caused to converge and in optical axis oflight of the blue wavelength band is made to coincide with the opticalaxis of the light guiding unit 75 by the collective lens system 155 sothat light of the blue wavelength band emitted from the blue lightsource (74 b) can be incident into the light guiding unit 75 via thelight guiding unit incident lens 154.

A secondary dichroic mirror 151 f is disposed in a position where theoptical axis of light of the red wavelength band emitted from the redlight source (74 a) and the optical axis of light of a blue wavelengthband emitted from the blue light source (74 b) intersect each other.

The secondary dichroic mirror 151 f reflects light of the red wavelengthband and light of the green wave length band and allows light of theblue wavelength band to pass therethrough. Light which has beenreflected by the secondary dichroic mirror 151 f and light which haspassed through the secondary dichroic mirror 151 f are each caused theiroptical axes to coincide each other to converged by the light guidingunit incident lens 154 so as to be incident into the light guiding unit75, as well as the embodiment that has been described by reference toFIGS. 3 and 4.

Three types of luminescent material layers are formed of green lightemitting luminescent materials on the optical wheel 71′ of the lightsource unit 63′ so as to attain a high lightness/saturation mode, a highluminance mode, and a normal mode. Specifically, as shown in FIG. 9,there are provided a primary light emitting area 1, a secondary lightemitting area 2, and a tertiary light emitting area 3, each of whichforms respectively a primary luminescent material layer 1 b whichutilizes a luminescent material for high lightness/saturation havinghigh color purity, a secondary luminescent material layer 2 b whichutilizes a luminescent material for high luminance having high luminanceproperty, and a tertiary luminescent material layer 3 b which utilizes aluminescent material having average luminance and saturation.

As shown in FIG. 10(A), when a projector projects images in the highluminance mode, a light source control circuit 41 for executing acontrol of turning-on the light source unit 63′ controls turn-on timingsof the red light source (74 a), the excitation light source 72, and theblue light source (74 b) sequentially, and also controls a rotationtiming of the optical wheel 71′ so that light emitted from theexcitation light source 72 is incident into the secondary luminescentmaterial layer 2 b for the high luminance mode.

As shown in FIG. 10(B), when the projector projects images in the highlightness/saturation mode, the light source control circuit 41 controlsturn-on timings of the red light source (74 a), the excitation lightsource 72, and the blue light source (74 b) sequentially, and alsocontrols a rotation timing of the optical wheel 71′ so that lightemitted from the excitation light source 72 is incident into the toeprimary luminescent material layer 1 b for the high lightness/saturationmode.

In addition, as shown in FIG. 10(C), when the projector projects imagesin the normal mode, the light source control circuit 41 controls turn-ontimings of the red light source (74 a), the excitation light source 72,and the blue light source (74 b) sequentially, and also controls arotation timing of the optical wheel 71′ so that light emitted from theexcitation light source 72 is incident into the tertiary luminescentmaterial layer 3 b for the normal mode.

Note that electric voltage or an effective value of applied voltagewhich is applied to the light emitting light source 74 should beadjusted depending upon which light emitting area among the primarylight emitting area 1 to the tertiary light emitting area 3 theexcitation light to be shone on to.

Therefore, the projector having the light source unit 63′ can reduce aluminance difference between each light of color wavelength bands. Inaddition, the projector can permit projections in different modes byutilizing effectively a whole circumference of the optical wheel 71′ hproviding the optical wheel 71′ with luminescent material layers whichemit green light having different lightness or saturation and in formingany non-use area on the whole circumference.

Additionally, the whole circumference of the optical wheel may bedivided into four light emitting areas, as shown in FIG. 11, forproviding a quaternary luminescent material layer 4 c in one of thelight emitting areas so divided which is a quaternary light emittingarea 4. In the it three out of four light emitting areas, a primaryluminescent material layer 1 c is formed which is a green light emittingluminescent material having high color purity in a primary lightemitting area 1, a secondary luminescent material layer 2 c is formedwhich is a green light emitting luminescent material having highlightness in a secondary light emitting area 2, and a tertiaryluminescent material layer 3 c is formed which is a green light emittingluminescent material having average luminance and saturation in atertiary light emitting area 3, as described in the above embodiment.

The light source control circuit 41 executes a control of turning-on thered light source (74 a) and the blue light source (74 b) while shiningexcitation light on to one of the light emitting areas, from the primarylight emitting area 1 to the tertiary light emitting area 3. Further,the light source control circuit 41 shines excitation light on to partof the quaternary luminescent material layer 4 c which is an yellowlight emitting luminescent material of the quaternary light emittingarea 4 while the red light source (74 a) or the blue light source (74 b)is turned on to thereby add light of an yellow wavelength hand to lightof the red wavelength band or to light of the blue wavelength band whichare emitted from the independent light source 74. By these controls ofthe light source control circuit 41, luminance of a projected image canbe increased.

In addition, as shown in FIG. 12, there may be a case that in order toincrease luminance of a projected image, the light source controlcircuit 41 executes a control of turning on the excitation light source72 so as to shine excitation light on to the secondary luminescentmaterial layer 2 c of the secondary light emitting area 2 and thequaternary luminescent material layer 4 c of the quaternary lightemitting area 4, and simultaneously executes a control of turning on thered light source (74 a) and the blue light source (74 b) to thereby addlight of the yellow wavelength band emitted from an optical wheel 71″ tolight of the red wavelength band emitted from the red light source (74a), light of a green wavelength band emitted from the optical wheel 71″,and light of the blue wavelength hand (74 b).

Furthermore, the projector 10 comprising the light source unit 63′ canproject white light by light of the yellow wavelength band emitted fromthe optical wheel 71″ having the Quaternary luminescent material layer 4c which is the yellow light emitting luminescent material in thequaternary light emitting area. 4 and fight of the blue wavelength bandemitted from the blue light source (74 b).

Note that the invention is not limited to the embodiment that has beendescribed heretofore and hence can be freshly modified or improvedwithout departing from the spirit and scope of the invention.

The invention claimed is:
 1. A projector comprising: a light source unitwhich comprises: (i) an optical wheel having a plurality of segmentareas, including luminescent light emitting areas where at least twoluminescent material layers having different characteristics areprovided side by side in a circumferential direction; (ii) a wheel motorfor driving to rotate the optical wheel; (iii) an excitation lightsource for shining light onto the optical wheel as excitation light oras light of a predetermined wavelength band; (iv) a light emittingelement provided out of an optical path of the optical wheel; and (v) alight guiding optical system for guiding a light beam emitted from theoptical wheel and a light beam emitted from the light emitting elementto converge to a same optical path, wherein the excitation light sourceis selectively turned on to selectively illuminate the at least twoluminescent material layers having different characteristics which arelaid on the luminescent light emitting areas by discriminating theluminescent material layers into an area onto which the excitation lightis shone and an area onto which the excitation light is not shone, andwherein the light emitting element is turned on for a period of timeduring which the excitation light source does not shine the excitationlight; a light guiding unit; a display device; a projection opticalsystem; and a projector controller including a light source controllerand a display device controller, wherein the projector is configured toperform projection in different projection modes including a primaryprojection mode and a secondary projection mode, wherein the lightsource unit is disposed so that light emitted from the light source unitis caused to converge to an incident plane of the light guiding unit,wherein the projector controller switches the luminescent materiallayers on the optical wheel between an area onto which the excitationlight is shone and an area onto which the excitation light is not shonein the primary projection mode and the secondary projection mode,wherein in the optical wheel of the light source unit, a primaryluminescent light emitting area and a secondary luminescent lightemitting area where the luminescent material layers are formed and adiffusion and transmission area are provided side by side in acircumferential direction, wherein in the primary projection mode, theprojector controller controls the light source controller so as toexecute a control of turning on the excitation light source and turningoff the light emitting element when the diffusion and transmission areaand the primary luminescent light emitting area are positioned on anoptical axis of light emitted from the excitation light source and acontrol of turning off the excitation light source and turning on thelight emitting element when the secondary luminescent light emittingarea is positioned on the optical axis of light emitted from theexcitation light source, and the projector controller controls thedisplay device controller so as to produce images in the order of lightemitted from the diffusion and transmission area, light emitted from theprimary luminescent light emitting area, and light emitted from thelight emitting element, and wherein in the secondary projection mode,the projector controller controls the light source controller so as toexecute a control of turning on the excitation light source and turningoff the light emitting element when the diffusion and transmission areaand the secondary luminescent light emitting area are positioned on theoptical axis of light emitted from the excitation light source and acontrol of turning off the excitation light source and turning on thelight emitting element when the primary luminescent light emitting areais positioned on the optical axis of light emitted from the excitationlight source, and the projector controller controls the display devicecontroller so as to produce images in the order of light emitted fromthe diffusion and transmission area, light emitted from the lightemitting element, and light emitted from the secondary luminescent lightemitting area.
 2. A projector as set forth in claim 1, wherein theexcitation light source is a blue laser emitter, wherein the lightemitting element is a red light emitting diode or a red laser emitter,and wherein the luminescent material layers include at least a greenluminescent material.
 3. A projector as set forth in claim 2, whereingreen luminescent material layers which can emit different types oflight of green wavelength bands which have different hues are formed,respectively, as the at least two luminescent material layers havingdifferent characteristics.
 4. A projector as set forth in claim 3,wherein the green luminescent material layers which can emit differenttypes of light of green wavelength bands which have different huesinclude green luminescent material layers which can emit different typesof light of green wavelength bands which have at least one of (i)different central wavelengths of emission spectra and (ii) differentwavelength bands at half-power points of the emission spectra.
 5. Aprojector as set forth in claim 2, wherein the at least two luminescentmaterial layers having different characteristics include greenluminescent material layers which can emit different types of light ofgreen wavelength bands, the green luminescent material layers comprisinga same luminescent material, and the luminescent material beingcontained in the respective luminescent material layers at differentratios.
 6. A projector as set forth in claim 2, wherein the at least twoluminescent material layers having different characteristics includegreen luminescent material layers which can emit different types oflight of green wavelength bands, the green luminescent material layershaving different thicknesses.
 7. A projector as set forth in claim 6,wherein the green luminescent material layers comprises a sameluminescent material, and the luminescent material is contained in therespective luminescent material layers at a same ratio.
 8. A projectoras set forth in claim 1, wherein in the optical wheel, at least areas ofthe luminescent light emitting areas where the luminescent materiallayers are laid are formed as reflecting planes.